This invention relates to implantable infusion pumps for controlled delivery of a selected infusant and more particularly to implantable infusion pumps that generate volumes of gas that are utilized in administering desired quantities of a selected fluid to a patient (i.e. a person or animal being treated or benefited by the fluid).
Implantable infusion pumps currently utilize either an active electromechanical pump or a gas propellant driven xe2x80x9cconstant flowxe2x80x9d system. The former devices are generally programmable and use a battery and electronic circuitry to cause a rotary peristaltic pump or a piston pump to deliver a selected fluid (e.g. drug, medication, or protein) that is stored in a reservoir according to a preset delivery profile or one that can be set by the patient or a health care professional. An example of such a device is found in U.S. Pat. No. 4,573,994 to Fischell. This patent is hereby incorporated herein, in full, by this reference.
The latter devices are currently non-programmable and deliver the fluid at an essentially constant rate by driving a bellows reservoir with pressure created by a propellant such as FREON. An example of such a device is found in PCT publication WO 98/56443, to Mann, et al., published Dec. 17, 1998. This PCT application claims priority to U.S. patent application Ser. No. 08/871,830, filed on Jun. 7, 1997. This PCT publication and U.S. patent application are hereby incorporated herein, in full, by this reference.
A need exists in the art for pumps with improved features such as reduced size, and/or reduced cost.
It is a first object of selected embodiments of the present invention to provide a an implantable infusion system of reduced size.
It is a second object of selected embodiments of the present invention to provide an implantable infusion system having reduced cost.
A first aspect of the invention provides an implantable infusion pump for dispensing a fluid to a patient, including: (1) a pump housing capable of being implanted in a body of a patient; (2) an inlet in the housing for receiving the fluid to be dispensed; (3) an outlet in the housing from which fluid is dispensed; (4) a first reservoir of variable size for holding the fluid, wherein the inlet and first reservoir are at least periodically connected by a flow path so as to allow fluid supplied to the inlet to flow to the first reservoir, and wherein the outlet and first reservoir are at least periodically connected by a flow path so as to allow fluid in the first reservoir to be dispensed through the outlet; (5) a second reservoir of variable size for holding a gas; (6) a volume comprising the first reservoir and the second reservoir, such that as the second reservoir expands in size the first reservoir diminishes in size; and (7) a gas generating source for controllably and variably producing quantities of gas that expand the size of the second reservoir, thereby decreasing the size of the first reservoir to cause dispensing of fluid through the outlet to the patient.
A second aspect of the invention provides a method for infusing a fluid into a body of a patient, including: (1) providing an implantable device in a patient, wherein the implantable device includes a volume that is partitioned into a first reservoir of variable size and a second reservoir of variable size, such that as the second reservoir expands in size the first reservoir diminishes in size; (2) providing fluid to a first reservoir; and (3) generating and providing within the implantable device quantities of a gas on a controllable and variable basis to the second reservoir to cause expansion of the second reservoir such that a portion of a volume of the first reservoir is diminished and a portion of the fluid originally supplied to the first reservoir is dispensed through an outlet of the implanted device into the body of the patient.
A third aspect of the invention provides an implantable device for dispensing a drug to a patient, including: (1) a means for holding a fluid that may be electrolyzed; (2) a means for causing a selected amount of the fluid to be electrolyzed to produce a gas; (3) a means for separating produced gas from the fluid and allowing the gas, but not the fluid, to pass to a volume surrounded by a variable size containment means; (4) a reservoir means for holding a drug to be dispensed, the reservoir means being of variable size and located in relation to the containment means such that as the containment means increases in size the reservoir means decreases in size thereby dispensing the drug to the patient; (5) a means for refilling the reservoir with the drug; and (6) an means to remove gas from inside the containment means so that refilling of the reservoir means may occur.
While certain objectives and aspects of the invention have been noted above, other objectives and aspects will be apparent to those of skill in the art upon study of the teachings herein. It is not required that each aspect of the invention simultaneously address all of the objectives of the various embodiments. Each aspect of the invention may address a single one of the objectives or alternatively might address a combination of two or more objectives.
Embodiments of the invention provide implantable infusion pumps that use a process of converting at least one chemical substance (first chemical substance) to at least one gaseous substance (second chemical substance), e.g. by electrolysis, to provide a motivating force to expel a desired fluid (e.g. drug, medication, or protein) from the pump into the body of a patient.
Some embodiments provide an expandable sack around a gas producing electrolytic cell, such that as the gas expands it displaces a portion of the volume originally allocated to the desired fluid, and thereby forces the fluid from the pump.
Some embodiments provide pumps with a double septum to allow refilling of the desired fluid while simultaneously allowing removal of the generated gas from the system while using a single needle.
Some embodiments provide recharging of pump batteries by direct electrical conduction through one or more needles and/or by inductive or radio frequency energy transfer.
Some embodiments provide programming of the pump by way of conductive paths provided by one or more needles or by means of inductive or radio frequency transfer.
Some embodiments provide a pressure regulator in the vicinity of an outlet port of the pump so as to enable more reliable operation of the pump when subjected to changes in ambient pressure.
Some embodiments provide a one-way valve to reduce risk of back flow into the pump.